ABSTRACT This competing renewal exploits a conserved fungal antigen to vaccinate against the three major systemic my- coses of North America, Blastomycocis, Coccidiodomycosis and Histoplasmosis, and elucidate the mechanics that underpin vaccine induced CD4 T cell memory immunity elicited against these pulmonary fungal infections. While host resistance against respiratory pathogens is thought to reside with lung tissue-resident memory cells (Trm) and mucosal immunity, our strong preliminary data unexpectedly reveal that systemic vaccination elicits a population of migratory T cells that confer protection, whereas Trm elicited at the lung mucosa do not protect. We have discovered a novel fungal ligand for dectin-2, Blastomyces endoglucanase 2 (Bl-Eng2), that is an ad- juvant and an immune-dominant antigen that confers vaccine immunity. We have also developed MHCII: pep- tide tetramers to enable in vivo tracking of Eng2-specific migratory and lung-resident CD4 T cells. Importantly, Eng2 is conserved Blastomyces, Coccidiodes and Histoplasma, the agents of endemic mycoses. We propose to identify Eng2 T cell epitopes that confer protection against the endemic mycoses and uncover correlates of protective immunity during the systemic vaccine priming and effector phases. We hypothesize that migratory T cells confer vaccine immunity by homing to lung via CX3CR1 and CXCR3 mediated chemotaxis. We aim to: 1. Elucidate the role of migratory T cells and their homing receptors in vaccine resistance. We will use adoptive transfer, parabiosis and SIPR1 blockade of T egress from the SLO to identify the functional and phenotypic features of protective CD4 T cells and determine the roles of CX3CR1 and CXCR3 in migration. 2. Pinpoint priming events that elicit protective, migratory T cells. We will identify accessory cells that transport Eng2 to the lymph nodes, display peptide and prime nave T cells, and define by fate mapping of T cells whether phenotypes are irreversibly set locally in draining LN or display plasticitity on recall to lung. 3. Identify Eng2 T cell epitopes that protect mice against infection and are recognized by humans. We will use an immunoinformatic algorithm to identify Eng2 T cell epitopes that protect C57BL6 and ?humanized? HLA-DR4 mice against the endemic mycoses and are recognized by humans recovered from the diseases. Our work will exploit a conserved fungal antigen to vaccinate against multiple systemic mycoses. We will use this vaccine to unveil conceptually new insight about how antifungal CD4 T cells are ideally primed systemi- cally, and divine the mechanics by which they migrate to resist pulmonary infection. Our work will challenge emerging views about a critical role for Trm in the generation of mucosal resistance to respiratory infection.